Code Orange! Avoid Looking Like a Carrot
Most self-tanners contain dihydroxyacetone (DHA), a colorless sugar that interacts with the top layer of skin to darken. According to Locke, who works with Olivia Wilde, Katharine McPhee, and the cast of Dancing with the Stars, an orange tint is often due to an oversaturation of DHA—which can occur when you layer on too much product or use a self-tanner with a percentage of DHA too high for your skin type. "Some people can tolerate higher levels of DHA than others, based on their natural tone and skin pH," says Locke. "I have certain clients where I can put a tremendous amount of product on and they absorb it like a sponge and never get too dark or turn a strange color. Others, I'll do one light layer and they're ultratan." To determine how a self-tanning solution will work with your skin, Locke suggests applying a small amount to a test area before covering your entire body.

Besides avoiding the urge to slather on or spray loads of product, Locke says choosing the right formula also determines how your tan will appear. "Go with a reputable brand, one that uses a lower percentage of DHA so that you can build your color accordingly," she says. Bronze-seekers should also go for products infused with erythrulose, a sugar sourced from raspberries. The combination of DHA and erythrulose in a sunless tanning product is believed to yield longer-lasting, cosmetically pleasing color. Some self-tanners, like those found in the St. Tropez collection, also contain green pigment to help counteract any orange.

Pre-Tanning Prep: Create the Ideal Canvas
"The most important thing to do is exfoliate," says Baraf, who gives Victoria's Secret models Alessandra Ambrosio, Marisa Miller, and Miranda Kerr their photo-ready glow. To get the smoothest, streak-free color possible, Baraf emphasizes the necessity of applying self-tanner immediately after exfoliating: "The outer layer of the epidermis, which is what the self-tanner interacts with, is composed of dead skin cells that last only seven to 10 days before they shed. You want to make sure you have an even layer of dead skin cells so that they all tan and slough off together." If you don't properly exfoliate "some of the skin will begin peeling in a day or two," adds Baraf, which can result in a splotchy tan job.

Go for a scrub that is gentle (think spherical, man-made beads over granular ones with uneven edges) to avoid irritating the skin prior to tanning. The ideal scrub should also be oil-free ("an oil-based polish can act as a barrier between the self-tanner and top layer of the skin," says Locke). When in a bind, using a loofah or muslin cloth with water will do the trick too.

The next prep step varies depending on who you ask: "There are two camps of thought," says Baraf. "Some experts recommend moisturizing, while others think lotion gets in the way of the chemical reaction between the DHA and the skin." Baraf says she personally prefers skin to be moist and that a way to avoid the controversy is to use a gradual tan moisturizer: "A moisturizer that contains self-tanner is formulated to work with DHA, so you don't have to worry about it clogging the pores. Plus, if you miss a spot with the full-fledged self-tanner, you've already covered it with the gradual tanner."

For her part, Locke thinks skin should be dry pre-application but says she'll use a light layer of moisturizer on particularly dry areas like the elbows, hands, feet, ankles, and knees so that they don't overabsorb color. She favors St. Tropez self-tanner because it has hydrating aloe vera in it to help compensate for any dryness ("As soon as you put the product on, your skin feels hydrated"). Clarins self-tanning products also contain aloe vera, and the new Victoria's Secret BeachSexy Sun-Kissed Bronze Instant Self Tan Lotion includes hydrators like coconut oil and avocado oil.

Who Has Your Back? The Application Process
Self-tanning novices are best off using an easy-to-control mousse or gel with a wash-off cosmetic tint, say Baraf and Locke. "The advantage is that you can see what you're doing, and you won't miss any spots," says Locke. For self-tanner enthusiasts, however, both experts say an aerosol spray is the best option: "It's quicker—you can just throw a towel down in your shower and go for it," says Locke.

Guide color or not, pay close attention to what areas you've covered. "Start from the bottom of your body and work your way up so that you don't crease the color when you bend over," says Baraf, adding that those who use a spray should "always keep the bottle and wrist moving" for an even application.

When it comes to covering your back, Baraf suggests "looking over your shoulder, spraying into the air behind you, and stepping back into the mist—kind of like how you walk into perfume. Do this up to three times to ensure that enough of the product lands on your skin."

Contouring Secrets: Slim, Boost, and Define
To make cleavage worthy of a Victoria's Secret catalogue, Baraf says to don your favorite push-up bra a half hour after applying self-tanner. Next, use an aerosol spray tanner and mist the M-shaped indentation created by the bra. Spraying on this second coat will make the area appear darker and more defined.

Besides this optical illusion, Baraf believes that all other contouring endeavors should be done by a professional or with makeup to avoid a "stripe-y" appearance. For example, to thin thighs, use a powder body bronzer or long-wearing gel product to darken the sides: "Darker skin absorbs more light than it reflects and makes the sides of the legs recede," says Baraf. To further draw the eye inward, she says to dust highlighter down the center.